1. Field of the Invention
This invention relates to a method and apparatus for enforcing capacity limitations in a logically partitioned information handling system and, more particularly, to a method and apparatus for enforcing such capacity limitations in accordance with those imposed by the terms of a software program license agreement.
2. Description of the Related Art
As indicated above, this invention relates to the enforcement of capacity limitations, such as those imposed by a program license agreement, in a logically partitioned system. As a preliminary to discussing the problems that are addressed by the invention, a brief discussion of logically partitioned systems and existing methods of resource and workload management is in order.
Logical partitioning is a concept that originated on a predecessor to the current IBM S/390 computer hardware platform. Today, many S/390 hardware machines operate in what is known as logically partitioned (LPAR) mode, in which the physical resources of the machine are partitioned to form a plurality of logical machines called logical partitions. More particularly, each logical partition appears to programming running in the partition as a logical machine that is similar in behavior to the actual physical machine, but has a subset of that machine's resources.
Logical partitioning allows the establishment of a plurality of system images within a single physical central electronics complex (CEC), or central processor complex (CPC) as it is alternatively called. Each system image is capable of operating as if it were a separate computer system. That is, each logical partition can be independently reset, initially loaded with an operating system that may be different for each logical partition, and operate with different software programs using different input/output (I/O) devices. Logical partitioning is in common use today because it provides its users with flexibility to change the number of logical partitions in use and the amount of physical system resources assigned to each partition, in some cases while the entire central processor complex continues to operate.
Logically partitioned computer systems are well known in the art and are described in U.S. Pat. No. 4,564,903 (Guyette et al.), U.S. Pat. No. 4,843,541 (Bean et al.), and U.S. Pat. No. 5,564,040 (Kubala), incorporated herein by reference. Commercial embodiments of logically partitioned systems include IBM S/390 processors with the Processor Resource/Systems Manager™ (PR/SM™) feature and described, for example, in the IBM publication Processor Resource/Systems Manager Planning Guide, GA22-7236-06, June 2000, incorporated herein by reference.
Workload management is a concept whereby units of work (processes, threads, etc.) that are managed by an operating system are organized into classes (referred to as service classes or goal classes) that are provided system resources in accordance with how well they are meeting predefined goals. Resources are reassigned from a donor class to a receiver class if the improvement in performance of the receiver class resulting from such reassignment exceeds the degradation in performance of the donor class, i.e., there is a net positive effect in performance as determined by predefined performance criteria. Workload management of this type differs from the conventional resource management performed by most operating systems in that the assignment of resources is determined not only by its effect on the work units to which the resources are reassigned, but also by its effect on the work units from which they are taken.
Workload managers of this general type are disclosed in the following commonly owned patents, pending patent applications and non-patent publications, incorporated herein by reference:                U.S. Pat. No. 5,504,894 to D. F. Ferguson et al., entitled “Workload Manager for Achieving Transaction Class Response Time Goals in a Multiprocessing System”;        U.S. Pat. No. 5,473,773 to J. D. Aman et al., entitled “Apparatus and Method for Managing a Data Processing System Workload According to Two or More Distinct Processing Goals”;        U.S. Pat. No. 5,537,542 to C. K. Eilert et al., entitled “Apparatus and Method for Managing a Server Workload According to Client Performance Goals in a Client/Server Data Processing System”;        U.S. Pat. No. 5,603,029, to J. D. Aman et al., entitled “System of Assigning Work Requests Based on Classifying into an Eligible Class Where the Criteria Is Goal Oriented and Capacity Information is Available”;        U.S. application Ser. No. 08/383,168, filed Feb. 3, 1995, of C. K. Eilert et al., entitled “Apparatus and Method for Managing a Distributed Data Processing System Workload According to a Plurality of Distinct Processing Goal Types”, now U.S. Pat. No. 5,675,739;        U.S. application Ser. No. 08/383,042, filed Feb. 3, 1995, of C. K. Eilert et al., entitled “Multi-System Resource Capping”, abandoned in favor of U.S. application Ser. No. 08/848,763, filed May 1, 1997, now U.S. Pat. No. 6,442,583;        U.S. application Ser. No. 08/488,374, filed Jun. 7, 1995, of J. D. Aman et al., entitled “Apparatus and Accompanying Method for Assigning Session Requests in a Multi-Server Sysplex Environment”, now U.S. Pat. No. 6,249,800;        MVS Planning: Workload Management, IBM publication GC28-1761-00, 1996;        MVS Programming: Workload Management Services, IBM publication GC28-1773-00, 1996.        
Of the patents, U.S. Pat. Nos. 5,504,894 and 5,473,773 disclose basic workload management systems; U.S. Pat. No. 5,537,542 discloses a particular application of the workload management system of U.S. Pat. No. 5,473,773 to client/server systems; U.S. Pat. Nos. 5,675,739 and 6,442,583 disclose particular applications of the workload management system of U.S. Pat. No. 5,473,773 to multiple interconnected systems; U.S. Pat. No. 5,603,029 relates to the assignment of work requests in a multi-system complex (“sysplex”); and U.S. Pat. No. 6,249,800 relates to the assignment of session requests in such a complex. The two non-patent publications describe an implementation of workload management in the IBM® OS/390™ (formerly MVS®) operating system.
Recent logical partition clustering technology combines aspects of logical partition management and workload management. As described in the copending application of applicants J. P Kubala et al., Ser. No. 09/407,391, filed Sep. 28, 1999, and incorporated herein by reference, in one mode of operation LP manager 106 manages logical partitions 108 as groups referred to herein as LP clusters (LPCs), or simply clusters. A cluster may comprise all of the logical partitions 108 on a particular machine 102, a subset of the partitions 108 on a particular machine 102, or even partitions 108 from different machines 102. LP manager 106 may assign a specified amount of a machine resource (such as shared CPU capacity, in the case of the present invention) to a cluster as a whole. The cluster would be limited to that specified amount in the presence of resource contention, but would potentially be able to use an additional amount of such resource in the absence of contention.
In addition to allocating a share of machine resources to a cluster as a whole, LP manager 106 is capable, in this mode of operation, of allocating resources among the logical partitions 108 making up a cluster in accordance with logical partition weights that are assigned to the respective partitions. As an example of this weighting, consider an LP cluster that consists of four logical partitions (LP1–LP4) and has available to it a total CPU capacity of 400 MIPS (millions of instructions per second). Assume that LP1–L4 are assigned respective weights of 20, 30, 40 and 10, for a total cluster weight of 100. In this example, if there is CPU contention, then partitions LP1–LP4 are allowed to run at respective capacities of 80 MIPS, 120 MIPS, 160 MIPS and 40 MIPS, for a total capacity equal to the cluster capacity of 400 MIPS.
With this background, the problem addressed by the present invention can be discussed. Primarily, it relates to the manner in which software for server platforms such as S/390 is licensed. Today much of S/390 software, both IBM software and vendor software, is priced based on the size of the physical machine on which it runs. An application that is run on a machine (references here to “machines” are to physical machines) with one central processor unit (CPU) is less expensive than the same application run on a machine with 10 CPUs. The price is independent of the amount of work actually done by the application.
This pricing scheme can cause end users to build less than optimal configurations to lower software costs. For example, if a user wanted to start a small-scale experiment with a new software product, the user might bring in a small machine to run this new product instead of running it on an existing large machine to keep the software price down. This entails the additional management overhead of dealing with another machine and does not allow the installation to take advantage of the logical partition clustering technology referred to above. These problems are aggravated by the fact that the sizes of S/390 machines are growing faster than many customer workloads.
To state it somewhat differently, today on the S/390 platform software is most often licensed to an entire machine. With the pricing of most software being based on the total capacity of the machine on which it runs (typically expressed as millions of instructions per second, or MIPS), increasing the capacity of a machine drives up a user's software licensing costs. If a given program product is used across the entire capacity of the machine, this is not necessarily a bad proposition or model for the end user or the vendor. However, if a program product is meant to be used on a portion of the machine, in a logical partition, having to license that product to the entire capacity of the machine is an expensive undertaking.
Part of the strength of the S/390 platform is its ability to run multiple, diverse workloads in multiple logical partitions to make efficient use of the hardware resources. In attempting to move new workloads (such as UNIX based applications and Web servers) onto the S/390 platform, it would be desirable to be able to add these new workloads to existing machines alongside existing applications and corporate databases that already reside on S/390. However, with machine-based software pricing, the entry cost into the S/390 world for these workloads is not cost competitive with alternate platforms.